Social Studies · Canada
Supply, Demand, and Price
Why does the price of strawberries drop every summer? Three simple ideas explain it, and they show up all over the CAEC Economics questions.
Picture a roadside fruit stand in the Niagara region in July. Strawberries are everywhere, and a basket costs almost nothing. By December, the same basket, now shipped from far away, costs three or four times as much. Nothing changed about the strawberries themselves. What changed was supply and demand, and together they set the price.
This is one of the most useful ideas in all of economics, and the good news is that it is built on plain common sense. Let's walk through it together.
The three words, in plain language
- Supply is how much of something sellers are able and willing to offer. Lots of strawberries ripening at once means a big supply.
- Demand is how much of something buyers want and are willing to pay for. When everyone wants strawberries for the long weekend, demand is high.
- Price is the amount of money the item actually sells for. Price is not set by one person, it settles at the point where supply and demand meet.
The two rules that drive everything
Almost every supply-and-demand question comes down to two simple cause-and-effect rules. Learn these and you can reason through the rest.
When demand goes up (more people want it) and supply stays the same, the price tends to rise. When demand falls, price tends to fall.
When supply goes up (more of it available) and demand stays the same, the price tends to fall. When supply drops, price tends to rise.
Notice the pattern: scarcity (less supply, or more demand chasing the same goods) pushes prices up. Plenty (more supply, or weaker demand) pushes prices down.
Worked example: strawberries through the year
Let's follow one basket of Ontario strawberries across the seasons and watch the price move. As you read each row, ask yourself: is supply high or low? Is demand high or low?
| Season | Supply | Demand | Price per basket |
|---|---|---|---|
| Mid-July (local harvest) | Very high | Steady | $3 |
| September (season ending) | Falling | Steady | $5 |
| December (imported) | Low | Steady | $9 |
Seeing it on a supply and demand chart
Economists draw this idea as two crossing lines. The CAEC often shows a chart like this and asks you to read it, so it is worth getting comfortable with the shape.
A simplified supply and demand chart. The lines cross at the equilibrium price.
- The demand line slopes down to the right: when prices are low, buyers want more; when prices are high, they want less.
- The supply line slopes up to the right: when prices are high, sellers are happy to offer more; when prices are low, they offer less.
- Where the two lines cross is the equilibrium price, the price where the amount buyers want exactly matches the amount sellers offer.
Reading an economic source carefully
The CAEC rewards careful reading, not guessing. Here is a short news-style source. Notice how one reader jumps to a conclusion while the other sticks to what the cause-and-effect actually shows.
"A late frost across Quebec and Ontario this spring damaged many apple orchards, leaving far fewer apples than usual heading into the fall. Grocery shoppers are already seeing higher prices at the produce aisle."
Adapted news report (illustrative example for study).
"Apple prices went up, so people must suddenly want a lot more apples." This guesses at demand, but the source never says demand rose, it says the harvest was damaged.
"The frost reduced the supply of apples. With fewer apples available and demand unchanged, the price went up." This matches Rule 2 and the actual cause in the text.
The trick on test day: identify whether the source is describing a change in supply or in demand, then apply the matching rule. Do not add information the source did not give you.
Tips that make these questions easier
- Find the cause first. Ask, "Did something change the supply or the demand?" A drought, a strike, or a factory closing usually changes supply. A new trend, a holiday, or population growth usually changes demand.
- Then apply the matching rule. Less supply or more demand means prices rise. More supply or less demand means prices fall.
- Use "scarce vs. plentiful" as a gut check. If something becomes harder to get, expect it to cost more. If it becomes easy to get, expect it to cost less.
- Stick to the source. On reading questions, only use what the chart or passage actually states. Do not assume a second factor changed unless you are told.
Your turn: practice questions
For each one, decide whether supply or demand changed, then predict what happens to the price. Try before you peek.
- A popular new phone is released and shoppers line up for weeks, but the factory can only make a limited number. What happens to the price?
- A bumper wheat harvest across the Prairies fills every silo, far more than usual. With demand about the same, what happens to the price of wheat?
- On the chart in this lesson, the supply line and the demand line cross at one point. What is that point called, and what does it tell you?
Tap to reveal the answers
- 1. Demand is high while supply is limited. Lots of buyers chasing few phones pushes the price up. (More demand, same or low supply means a higher price.)
- 2. Supply went way up while demand stayed the same, so the price falls. When something becomes plentiful, it tends to get cheaper, that is Rule 2.
- 3. It is the equilibrium price. It tells you the price at which the quantity buyers want to buy equals the quantity sellers want to sell, the market's balancing point.
Why this matters for the CAEC
The CAEC Social Studies test is 40 questions in 90 minutes, and Economics is one of its four domains. Supply, demand, and price show up directly, and the test leans heavily on reading charts, tables, and short sources, which is exactly the skill you just practised here.
Want more like this? Explore more Social Studies lessons, build your skills with the CAEC Ready Workbook, or try a free sample to see where you stand.
Disclaimer
This article is a general study lesson. CAEC Ready is an independent study resource and is not affiliated with or endorsed by any government, ministry of education, or official CAEC testing provider.